Barnwood Paneling for Garden Office

Hey folks, I am starting a remodel on a new shed to turn it into a garden office. The shed is fairly small (8x12 interior) and I intend to to R19 in the ceiling and R13 in the walls. It's built on 16" centers.

So my question is regarding using 1x6"x6' barn wood to panel the walls. Would I need to put something under them to help seal the building? Right now it's going to have tyvek and solid wood siding on the sides.

Barnwood Paneling for Garden Office

OK, the plans have changed, it seems the barnwood will be moved to the vaulted ceiling. 2x6 with rafter vents and R19 insulation. Could I just do plastic barrier over the rafters for dust/insulation containment and then put the barnwood over that?